FIG. 1 illustrates a molten metal feed apparatus disclosed in U.S. Pat. No. 7,021,361. The feed apparatus is used to feed molten metal to a die casting machine 11, and includes a ladle 12 for holding molten metal, and a conveyor system 13 for conveying the ladle 12 to a feed position of the die casting machine 11 and for tilting the ladle 12 to pour the molten metal into the die casting machine 11. Since an open space design of the feed apparatus does not favor preservation of the temperature of the molten metal, constant heating is required, which leads to high energy consumption. Furthermore, the temperature of the molten metal drops considerably and the molten metal may oxidize while the molten metal is being conveyed, which may result in defects during the die casting operation that can reduce the production yield.
FIGS. 2 and 3 illustrate an aluminum-based material melting apparatus disclosed in U.S. Patent Application Publication No. 2014/0054832. The apparatus includes a furnace unit 2 and a feed unit 3. The furnace unit 2 includes a closed furnace 21 in spatial communication with the feed unit 3. The feed unit 3 includes a feed hopper 31 for receiving particulate aluminum-based raw material, a pre-heating funnel 32, a valve mechanism 33 provided between the feed hopper 31 and the pre-heating funnel 32, and a conveying unit 34. When the weight of the particulate raw material becomes sufficient, the valve mechanism 33 changes to an open state, thereby permitting passage of the raw material into the pre-heating funnel 32. The raw material is conveyed from the pre-heating funnel 32 to the closed furnace 21 via the conveying unit 34, and is heated for melting in the closed furnace 21.
However, the melting apparatus requires pre-processing of the raw material into particulate form. Moreover, the design of the valve mechanism 33 may lead to a large amount of the raw material being fed at once, which may reduce and does not favor preservation of the temperature of the melting operation. Frequent reheating may be needed, which increases energy consumption.